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      <img src="../logo.svg" class="logo" alt=""><h1>What is EJAM?</h1>
            
      
      <small class="dont-index">Source: <a href="https://github.com/USEPA/EJAM/blob/HEAD/vignettes/0_whatis.Rmd" class="external-link"><code>vignettes/0_whatis.Rmd</code></a></small>
      <div class="d-none name"><code>0_whatis.Rmd</code></div>
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<div class="section level2">
<h2 id="epas-ejam-tool-and-the-ejscreen-multisite-tool">EPA’s EJAM tool and the EJScreen Multisite Tool<a class="anchor" aria-label="anchor" href="#epas-ejam-tool-and-the-ejscreen-multisite-tool"></a>
</h2>
<p>The Environmental Justice Analysis Multisite tool (EJAM) is a
software toolkit developed by the United States Environmental Protection
Agency (US EPA). EJAM is what powers the “EJScreen Multisite Tool” – a
web application that is a part of <a href="https://www.epa.gov/ejscreen" class="external-link uri" target="_blank" rel="noreferrer noopener" title="https://www.epa.gov/ejscreen">EJScreen</a>. EJAM is also
available as an open-source software package for developers and
analysts.</p>
<p>EJAM lets you easily and quickly see demographic and environmental
information aggregated within and across hundreds or thousands of
places, all at the same time.</p>
<p>Using EJAM is like running an EJScreen report, but for hundreds or
thousands of places, all at the same time.</p>
<p>You can see a quick summary, explore interactive maps, tables, and
plots, and download a summary report or detailed spreadsheet.</p>
<p>Locations can be defined in a variety of ways, so EJAM can summarize
the following:</p>
<ul>
<li><p><strong>Conditions near any set of points</strong><br>
(e.g., proximity analysis of residents near all the EPA-regulated
facilities of a certain type). This can provide EJ-related information
about people who live in communities potentially affected by any of the
industrial facilities on a list, for example.</p></li>
<li><p><strong>Conditions within any areas you have defined on a
map</strong><br>
(e.g., if you have a shapefile of polygons/ zones based on measured or
modeled exposure or risk, or cities/neighborhoods, etc.).</p></li>
</ul>
<div class="section level3">
<h3 id="ejscreen-data-methods">EJScreen Data &amp; Methods<a class="anchor" aria-label="anchor" href="#ejscreen-data-methods"></a>
</h3>
<p>EJAM begins with EJScreen data and indicators. It uses the same
methods but in a way that is optimized for working with many locations
at once. The default demographic indicators are <a href="https://www.epa.gov/ejscreen/overview-demographic-indicators-ejscreen" title="https://www.epa.gov/ejscreen/overview-demographic-indicators-ejscreen" class="external-link">EJScreen
basic demographic indicators</a>, with the race/ethnicity subgroups and
many of the other selected demographic indicators that EJScreen
provides. The environmental indicators and EJ Indexes are also the ones
used in EJScreen.</p>
<p>The tool runs either a polygon-based or proximity-based analysis at
each location, just like EJScreen would provide a standard report for a
single location, except EJAM does this for each of a large number of
locations very quickly.</p>
</div>
<div class="section level3">
<h3 id="new-unique-features">New &amp; Unique Features<a class="anchor" aria-label="anchor" href="#new-unique-features"></a>
</h3>
<p><strong>Summarizing Across Locations</strong></p>
<p>Unlike what EJScreen was originally designed to be able to offer,
EJAM can calculate an aggregated summary of overall environmental
conditions and demographics for the average resident across all the
populations and all of the locations.</p>
<p>The summary report lets you quickly and easily see which demographic
groups live near the selected facilities or within defined areas. It
also provides new insights into which environmental stressors may affect
certain demographic subgroups disproportionately, to varying degrees,
near a regulated sector overall and at individual sites.</p>
<p>This allows EJ analysis to move beyond looking at a small number of
indicators for a few demographic groups, at one site in a single
permitting decision, to a more complete picture of conditions near a
whole set of facilities that is the focus of a risk analysis or a
proposed action or initiative, for example.</p>
<p><strong>Immediate Results (Speed)</strong></p>
<p>Compared to related GIS tools this new tool provides a ready-to-use
summary report, plus more flexibility, accuracy, and speed than other
tools have in the past. The website quickly provides results on the fly
– The software was optimized to be extremely fast (allowing realtime
exploratory work), while still using the same block-population
calculation EJScreen has been using, making it more consistent with how
EJScreen has always worked and more accurate than other approaches
(e.g., using “areal apportionment” of tracts or block groups, like some
other tools have used).</p>
<p><strong>Easy Ways to Specify the Places to Analyze</strong></p>
<p>The new tool also lets one pick locations through several different
approaches, such as - specifying facility points by industry categories
of various types (NAICS, SIC, EPA program, etc.) - providing a table of
point locations given as latitudes and longitudes - using shapefiles
with polygons (e.g., from the results of air quality modeling work) -
selecting Census units to compare, such as Counties.</p>
<p><strong>Open Source Well-Documented Extensible Software</strong></p>
<p>Also, the data and software are shared as reusable, well-documented
functions in an R package, to allow software developers or analysts to
take advantage of these resources in running their own analyses or
building or supplementing their own tools, websites, or mobile apps.</p>
<p><strong>Accuracy and Spatial Resolution</strong></p>
<p>EJAM and EJScreen use the same approach to characterizing populations
at each site, to maintain consistency and avoid any confusion. Compared
to other often-used approaches, EJScreen/EJAM use high-resolution
buffering to provide more accurate information about which populations
live inside a buffer, which is important in rural areas where a single
blockgroup can cover a very large area. For circular buffers, the
internal points of Census 2020 blocks are used, not areal apportionment
of block groups, to estimate where residents live within each block
group. This avoids the simplistic assumption that people are evenly
spread out within each block group. Instead, it uses blocks to get
information about which part of a block group is where residents
actually live. There are several million blocks in the US, as compared
with fewer than a quarter million block groups. The only more accurate
approaches are 1) to use areal apportionment of blocks (not block
groups), but that is very slow, or 2) to use something like the 30x30
meter grid EPA developed using dasymetric estimates of where people live
at even higher resolution than a block, but that requires large amounts
of storage and computer time.</p>
<p>EJAM calculations also take note of which residences are near which
sites, to avoid double-counting people in the summary statistics but
still allow a user to view results for one site at a time. This is
something other tools and analyses often cannot provide - when they
aggregate across sites they typically do not retain the statistics on
individual sites, and rarely if ever keep track of which communities are
near multiple facilities. Keeping track of this would also allow an
analyst to explore how many people are near multiple sites, or ask which
sites in communities that already have multiple sites nearby.</p>
<p>EJAM was designed so that it can provide an essentially continuous
distribution of distances, as distributed across blocks or people for
one or all of the nearby facilities. This enables exploration of the
complete picture of proximities, rather than using an arbitrary single
distance defining near versus far. The distribution can be sliced later
for the summary statistics at any distance, and can be summarized as a
distribution of distances within each demographic group.</p>
</div>
<div class="section level3">
<h3 id="data-updates">Data Updates<a class="anchor" aria-label="anchor" href="#data-updates"></a>
</h3>
<p>Annual data updates are synchronized with EJScreen data updates and
main version numbers, so EJScreen 2.32 (the updated version released in
August 2024) and EJAM 2.32 use the same data. Version 2.32 has ACS
2018-2022 block group demographics and Census 2020 block weights.</p>
</div>
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